FIGS. 8-10 of U.S. Reissue Pat. No. 28,990 illustrate the fetal electrode most commonly used in the United States today. The product comprises a curved form sustaining guide tube through which an electrode assembly can be delivered to a fetal presenting part (typically the scalp) during delivery. The electrode which engages the fetus is a coil that extends from the forward end of an electrode holder and can be rotated by means of a flexible drive tube passing through the guide tube and adapted to engage a plate-like maternal electrode extending from the rear of the plastic holder.
The electrode is attached to the fetus by turning the drive tube causing the spiral electrode to penetrate the fetal presenting part. After the electrode is attached, the guide tube and drive tube are removed leaving the electrode in place. Wires attached to the coil and maternal electrode are then attached to a fetal monitor so that the condition of the fetus can be monitored prior to birth.
During birth, the coil is removed from the fetus by unscrewing it. When this is done, because the sharp point of the coil is unprotected, it can cause injury to the physician or the patient.
The object of this invention is to provide a safety device which can be used to sheath the coil of a spiral electrode to prevent injury to the patient and physician both before and after the electrode is attached or removed from the fetus.